Stepping mechanism



M. P. CHAPLIN STEPPING MECHANISM Filed-Aug. 5. 1924 m 1/ m a a Patented July 19, 1927.

rarest orrics.

MERLE PEABODY CHAIPLIN, OF WHITE PIri lfilil'S. YORK, ASSIGNOR TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NE! YORK, N. Y., CORPORATION OF NEW YORK.

STEPPING MECHANISM.

Application filed August 5, 1924. Serial No. 730,178.

This invention relates to selector switches, and more particularly to selector switches used in automatic telephone systems. It is especially adapted for use in automatic telephone systems wherein selector switches are set under control of direct current impulses produced by a dial or some other similar impulse sending mechanism.

There area number of selector switches comprising stepping devices known and used in connection with impulse senders. in. usingthese devices, it has been found that tl e selector switch will not function propcrly it the impulses produced by the impulse send are distorted, and it has been found neceary to provide a circuit arrangement sometimes known as an auxiliary or boostercircuit for insuring the proper OliiQIRtiOIl of the selector switch. in conjunction with'the selector switches heretofore usech it has been necessary to employ a sensitive relayi generally known as an impulse relay, which has been made rcsponsire to the impulses produced by the impulse sender or dial and which in turn has reproduced impulses for setting the selector switch. It has been found necessary to employ an impulse relay in this manner because owing to the selector switch load, which the stepping mechanism is required to drive, it has heretofore been found impractical to operate the stepping mechanism directly under control of the impulse sender even though the impulses supplied to the stepping mechanism are not distorted.

The object of this invention is a selector switch which will operate properly, even though the impulses are somewhat distorted,"

without the aid of a booster circuit.

Another ob ect oi? this invention 15 selector switch capable of responding; directly to the impulses produced by thc dial or other impulse sending mechanism;

A feature of this invention is the use of two electromagnets, one of heavy and powertul construction capable of performing a considerable amount of work and the other of light construction capable of high speed operation and designed to perform only a small amount of work, with an interlocking arrangement controlled by both electromagnets to provide for maintaining the sameinterrelation of members.

i'tnother feature of this invention is the adjusting arrangement for the pawl of the high speed electromagnet.

i nother feature of this invention is the unitary I ructure and adj usting arrangement oi the. contact controlling mechanism.

Other features will appear from the de- '1. id description. c

In accordance with this invention, an electromagnet of it i onstruction and which is according gly very sensitive and capable of ojperatin at high speed, is set under control oi. (lit't t current impulses produced by a subscribers dial. As soon as this elcctromagne energized, a circuit is, closed-tor 1 secon electromagnet of heavy and powert'ul construction whicn'drives the load of the selector switch This second electromagnet self-interrupting and accordingly steps until Hi attainsthc settingpreviously taken by the s nsitive clectromagne't," when its ircuit opened and it once more comes est the brushes'of the selector switch being then set in accordance with the number of impulses produced ori inally by the siitiscribefs dial.

the dra ing comprising but a single sheetthe nvention is diagrammatically illustrated.

Fig. 6 shows another circuit arrangement which may be used for returning the switch to its normal position.

The structure consists of a sensitive electromagnet 1, adjustably secured at 2 to the bracket a l. which is permanently secured at 4-. to tlie main frame?) of the switch; The

armature 6 ot the sensitive electromagnet 1., 1

for driving the ratchet 22. The s ring 8 serves to restore the armature 6, a ter the circuit for the electromagnet 1 is opened, and the back stop screw serves, among other purposes, to limit the return movement of the armature 6- The relation between the fulcrum 7 and the pole piece of the electromagnet 1 is fixed, and the adjustment of the pawl 11 with relation to the ratchet 22 is obtained by means of twin clamp screws by means of which the sensitive electromagnet 1 is adjustably secured at 2 to the bracket 44.

The driving electromagnet 12 is screwed at 46 to the bracket 47, which is in turn secured at 14 and 15 to the main frame 5 of the selector switch. The driving armature 16 of the driving electromagnet 12 is a lever whose fulcrum is at 17. The driving armature 16 is extended at 18, and the driving pawl 20 is adjustably secured at 19 to this extension arm of the driving armature. The driving pawl 20 operates the ratchet 21, to which is connected the main lead of the selector switch. a

The relation between the fulcrum 17 and the pole piece of the driving electromagnet 12 is fixed and the pawl 20 is adjusted with respect to the ratchet 21 by means of the ad'ustin screws shown at 19.

t WilT be observed that the spring 48 for driving the ratchet 21 and the main load(i v the pole piece of the electromagnet 12, an

the load connected to the ratchet 21 are all on the same side of the pivot 17, and are all in the same plane. The spring 43 is provided to maintain the driving armature 16 in the proper position with respect to its fulcrum 17, it also serves to assist the main driving spring 48.

The mechanism for controlling the opening and closing of contact springs 41 and 42 as well as the springs themselves is all assembled as a unit and is adjustably secured to the main frame 5 by means of screws 49 and 50.

Pole piece 38 for the auxiliary armature 37 is brought in close proximity to the magnet 12 at a point 29 by meanr of the extension member 28 to provide magnetic flux for holding auxiliary armature 37.

It will be observed that the unitary structure of the contact controlling mechanism is pivoted at 51 on the face of the main frame 5 so that the position of the unit with respect to the driving armature 16 of the electromagnet 12 may be varied by means of the screws 49 and 50. The auxiliary armature 37 is secured at 52 to the unitary structure. The position of this armature controls the opening and closing of the contact springs 41 and 42 of the interrupter which is included in the electrical circuit of the electromagnet 12. The back-stop among other things, the limit of the backward movement of the driving armature 16. \Vhen th driving armature 16 is at rest, the flexible spring 40 presses against the auxiliary armature 37, forcing it into physical contact with the pole piece 38 and by overcoming the opposing tension of the contact spring 41 closing the contacts of the contact springs 41 and 42. \Vhen the armature 16 is first attracted by the magnetization of the pole piece of the driving electromagnet 12, the auxiliary armature 37 is held against the pol piece 38, and the contact s rings 41 and 42 are maintained closed. hen the driving armature 16 approaches the limit of its forward movement however, the lug 39 pressing against the auxiliary armature 37. forces it away from the pole piece 38. The contact springs 41 and 42 are thus opened and interrupt the electrical circuit of the driving electromagnet 12.

The sensitive electromagnet 1 is used to drive th ratchet 22, and the driving electromagnet 12 is used to drive the ratchet 21. 1

The ratchets 21 and 22 are freely and independently mounted upon the shaft As more clearly indicated in Fig. 3, the ratchet 22 is equipped with a cam 34 and the ratchet 21 is similarly equipped with a cam In the normal position of the switch, the cams 34 and 35 are in the position with respect to each other shown in Fig. 1. \Vhenever the ratchets 21 and 22 are not in the position with respect to each other which is shown in Fig. 1, the cams 34 and 35 will be in a position shown in Fig. 3, in which case the contact springs 26 and 27 will be allowed to close by the action of the lever 24. \Vhen the ratchets 21 and 22 are in the position with respect to each other indicated in Fig. 1, the lever 24 overcomes the tension of the contact spring 26 at the point 25, maintaining contact springs 26 and 27 open, but when the ratchets 21 and 22 are in the position indicated in Fig. 3, the tension exerted at 25 upon the contact spring 26 by the lever 24 is removed, and the contact springs 26 and 27 are closed.

The principle of operation is as follows: The sensitive electromagnet 1 is connected directly or under control of an impulse relay as desired, to an impulse sender. Let us assume the electromagnet 1 is directly connected to the dial 36 (Fi 4). When the dial 36 is operated and reiased, the circuit through the electromagnet 1 is interrupted and the electrol'nagnet 1 which is very sensitive, responds to the impulses thus produced, and the ratchet 22 is rotated by means of the pawl 11 controlled by the armature 6. The ratchet 22 advances step by step, depending upon the number of impulses transmitted in accordance with the digit dialed, and finally comes to rest at the end of the impulse screw 53 which is 1 adjustable, determines, train. As soon as the ratchet 22 is advanced move forward until the main driving pawl- 20 engages a new tooth in the ratchet 21 at which moment the lug 39 engages the aurziliary armature 37, forcing it away from the pole piece 38 thus opening the magnetic circuit including the armature 37 and the pole piece 38. The contact springs 41 and 42 are now opened by virtue of their spring tension,

thus opening the electrical circuit for the driving electromagnet 12 which is deenergized. The main driving spring t8 and the "fulcrum maintaining spring 43, which were tensioned during the torward movement of the main driving armature 16 now retract, and in so doing initiate the backward movement 01 main armature 16 and cause the main driving pawl 20 .to rotatethc. ratchet 21 one step. During the return movement of the main driving armature 16. the flexible spring 46 engages with the auxiliary arma ture 37, forcing it once more into contact with the pole piece 3.8.. In this position. the contact springs 11 and 42 are once more closed and the cycle of operations is repeated. It should be understood that when the flex ible spring 10 is disengaged from the armature 37 during the forward movement oi the main drivingarmature 16, the armature 37 remains in physical contact with pole piece 38, due to the magnetic flux in the magnetic circuit including the auxiliary magnet armature 37 and pole piece 38.. So long as the armature 37 is in contact with the pole piece 3'8, the contact springs 11 and 4.2 remain closed. This cycle of operations of the driving electromagnet 12 is repe ated,'nntil the ratchet- 21 is once more in the position with relation to ratchet 22 which is shown in Fig. 1, when the contact springs 26 and 27 are opened by the action of the lever .24 under control of the ratchet 22.

The ratchet 22 associated. with the sen sitive electromagnet 1, is entirely independent of the ratchet 21 associated with the driving electromagnet 12, The sensitive electroinagnet 1 is capable of high speed op eration and will follow the impulses produt ed by the dial 36. The electromagnet 12 of heavy and powerful construction and is designed to perform a considerable amount of work. As applied in this disclosure, its 'lunction is to drive the brush load of the se lector switch. It is obvious therefore that the electromagnet 12 will be comparatively slower in operation than the sensitive elect-romagnet 1, but as its speed of operation is not dependent upon the dial 316, this is not important- The .elecftnomagnet 12 therefore may operate and step the ratchet 21 rats slowly .as 'is necessary to the proper :operat'iom oi' the stepping mechanism, without in any way depending upon the speed of the dial.

216 or the sensitive ielectromagnet 1 for its time. oi operation. h-en .tl-ie ratchets 21 and are again properly interlocked they will occupy the position with respect to each other indicated in Fig. 1 and the circuit @01 1 trolled lay the contact springs 26 and 27 will be opened preventing the clectromagnct 12 from neoperating. The brushes .54 will now be properly centered upon a certain set 05f terminal :in the terminal bank of the selector swatch.

The return to normal of the switch may be controlled in various ways. Two typical methods of accomplishing the return to mor mal are shown in Figs..5 and 6.

In the arrangement shown in Fig. 5, the return to normal is accomplished in the following manner. An arc of terminals is provided and all the terminals except those representing the normal position of the switch ane strapped together as shown. When it is desired to return the switch to normal, the contact 42' is disconnected from the contact 27 and is connected to battery, at the same time the conductor 56 is closed connecting ground to all the terminals of thc arc A circuit is now closed from battery by way of contact 42 and armature 41, through the windings of the electroinagnets 1 and in parallel, brush 57., any strapped terminal in the are 55;, condnctor"56,.to ground. The elelctrcrnagnet 1 being sensitive operates immediately, but the electromagnet- 12 which is driving the switch "load is slower in :0 oration. 'When the electromagnct 12 li-na' ly operates, the cinciiit is opened at t2 and the sensitive electromagnet 1 and the driving electromagnet 12 release, advancing the ratcl-lets 22 and 21 respectively, another step. When the elec-tromagnet 12 releases, the operating circuit is again closed and the cycle of operations is repeated, until the brush 57 finally comes to rest upon either the terminal 58 or the terminal 59 indicating the normalposition of the switch. With the brush 57 resting upon either the terminal 58 or the terminal 59, the operating circuit as previously traced is permanently opened and the electromagnets 1 and 12 are deenerg'i'zcd, preventing the further operation of the selector switch.

An alternative method for restoring the switch to normal is shown in Fig. 6. In this case, when the sensitive electromagnet 1 is moved oil normal, cam 30 which normally 'is in engagement with the stud 31, is rotated, and the contact springs 32 and 33 are closed. WVhen it is desired to return not shown in Fig. 6, will be returned to normal by way of a circuit arrangement such as the one shown in Fig 4 which was used for advancing it from the normal position when the sensitive electromagnet 1 was set under control of the dial 36.

The continued operation of a selector switch causes minute particles of metal and of dust to settle upon the terminals of the bank of the selector switch. These particles tend to collect at the bottom of the switch bank under the influence of gravity. Heretofore in switches of this general character, it has been customary to rotate the brushes in such a direction that any suction which may be created by them in rotating tends to draw the particles of dust and metal back into the bank. To overcome this ditliculty, and at the same time to assist in removing the dust and metal particles from the terminal bank, the brushes of the switch in the present invention are designed to create a suction and are caused to rotate in a direc tion such that the suction produced by the brushes in rotating tends to aid the force of gravity exerted upon dust and metal particles lodged in the switch bank. To accomplish this, it has been necessary to revolve the switch brushes 54 in a direction op osite to the one heretofore used.

Vhatis claimed is: v

1. In a stepping mechanism, a device responsive to impulses, a driven member operated thereby, a stepping magnet, a driven member operated thereby, means for mechanically inter-relating the two driven members aforesaid, means for supplying impulses to the impulse responsive device whereby it is operated and its driven member is set. means responsive to the movement of the driven member last mentioned,.whereby the stepping magnet is operated and its driven member is caused to be stepped until the inter-relation between the driven members is once more resumed.

2. In a stepping mechanism, two electromagnets, driven members individual. to each of them having a definite mechanical interrelationship, means for supplying impulses to one of the elect-romagnets whereby it sets its driven member and changes the interrelationship firstexisting, means responsive to the movement of the driven member aforesaid for operating the other electromagnetwhich causes its driven member to be stepped until the inter-relation between the driven members is once more resumed.

In a stepping mechanism, an impulse responsive device, a driven member operated thereby, a second driven member, a stepping magnet for operating said second driven member, cooperating cams on said driven members, contacts controlled by said cams, and a circuit for said stepping magnet closed by said. contacts when said first driven mem- 3G! is moved relative to said second driven member.

4. In a stepping mechanism. an impulse responsive device. a driven member rotatable thereby, a second driven member. a stepping magnet for operating said second driven member. said members being laterally mv able with respect to each other, cooperating cams on said members, said cams being effective to cause said lateral movement when one of said members is rotated with respect to the other, contacts controlled bv said cams, and a self-interrupting circuit for said stepping magnet closed by said contacts.

5. A unitary electromagnetic mechanism for driving a ratchet comprising an electromagnet,- an armature therefor, a pawl. secured to the armature, said electromagnetic device, unitarily adjustable with respect to the ratchet.

6. In a selector switch, a stepping, magnet for operating said switch, a contact contro ling mechanism unitary in form controlled by saidmag'net, a pivot for attaching said contact mechanism to the stationary portion of said selector switch, and means for rocking said contact mechanism on said pivot whereby the adjustment of the contact controlling device is obtained.

In witness whereof, I hereunto subscribe my name this 29th day of July A. D., 1924.

MERLE PEABODY CHA PLIN. 

